ionization
the production of ions, the process of converting an atom into an ion, deals only with energy to overcome the electrostatic force that binds the electron to the nucleus, resulting in the formation of a positive atom and a dislodged negative electron
penumbra
fuzzy border of an object as imaged radiographically
filtration
the use of absorbing materials (ex. aluminum) for removing the low-energy x-rays from the primary beam
lead apron
a flexible lead shield used to protect the patients reproductive and blood forming tissues from scatter radiation
collimation
the restriction of the size and shape of the x-ray beam in order to reduce patient exposure
ALARA
a concept of radiation protection that states that all exposure to radiation must be kept to a minimum, or "as low as reasonably achievable
density
the overall darkness or blackness of an image
latent image
the pattern of stored energy on the exposed film; the invisible image produced when the film is exposed to x-rays and that remains invisible until the film is processed
latent period
the amount of time that lapses between exposure to ionizing radiation and the appearance of observable clinical signs
Compton scatter
one of the interactions of x-radiation with matter in which the x-ray photon collides with a loosely bound, outer shell electron and gives up part of its energy to eject the electron from its orbit. the x-ray photon loses energy and continues in a differe
intensifying screen
a device that transfers x-ray energy into visible light; the visible light in turn , exposes the screen film, these screens intensify the effect of x-rays on the film, with its use less radiation is required to expose screen film, and patient is exposed t
foreshortening
a term describing images of teeth that appear too short; it is a result of excessive vertical angulation
elongation
a term describing images of teeth that appear longer than the actual teeth; it is the result of insufficient vertical angulation
primary beam
the penetrating x-ray beam produced at the target of the anode and that exits the tube-head
radiation
a form of energy carried by waves or a stream of particles
general radiation
a form of radiation that occurs when speeding electrons slow down because of their interactions with the tungsten target in the anode - AKA- Bremstahlung or braking radiation
characteristic radiation
a form of radiation that occurs when a high speed electron dislodges an inner shell electron from an atom, causing excitation, or ionization of the atom
electromagnetic radiation
the propagation of wavelike energy through space or matter, the propagated energy is accompanied be electric and magnetic fields, thus the term electromagnetic. examples: cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light, ra
ionizing radiation
radiation capable of producing ions; includes particulate or electromagnetic radiation
particulate radiation
tiny particles of matter that possess mass, travel in straight lines, and also travel at high speeds
scatter radiation
a form of secondary radiation; results from x-ray beam that has been deflected from its path by the interaction with matter
secondary radiation
radiation created when the primary beam interacts with matter; it is less penetrating than primary radiaiton
contrast
how sharply dark and light areas are differentiated or separated on an image; the difference in the degrees of blackness (densities) between adjacent areas on a dental radio graph
scale of contrast
the range of useful densities seen on a dental image
long scale of contrast
a term describing an image with many densities, or many shades of gray; it results from the use of a higher kilo-voltage range
short scale of contrast
a term describing an image with only two densities, areas of black and white; it results from a lower kilo-voltage range
high contrast
a term describing an image with many very dark areas and very light areas and few shades of gray
low contrast
a term describing an image with many shades of gray and few areas of black and white
radiolucent
the portion of an image that is dark or black; this structure readily permits the passage of the x-ray beam and allows more x-rays to reach the receptor
radiopaque
the portion of an image that is light or white, this structure is one that resists the passage of the x-ray beam and limits the amount of x-rays that reach the receptor
kVp
the maximum of peak voltage that is used during an x-ray exposure. Low kVp=short scale=high contrast
High kVp=long scale=low contrast
wavelength
determines the energy and the penetrating power of radiation. Shorter wavelengths=more penetrating power
Longer wavelengths=less penetrating and more likely to be absorbed by matter
quality
is used to describe the mean energy or penetrating ability of the x-ray beam- the quality, or wavelength and energy of the x-ray beam is controlled by kilo-voltage
voltage
a measurement of force that refers to the potential difference between two electrical charges. Voltage= determines the speed of electrons that travel from the cathode to anode, When the voltage is increased- the speed of the electrons increases, the elect
volt
the unit of measurement used to describe the potential that drives an electrical current through a circuit
kilovolt
1 likovolt is = 1000 volts
kilo-voltage
can be adjusted according to the individual diagnostic needs of the patient. the use of 85 to 100 kV produces more penetrating x-rays with greater energy and shorter wavelengths, 65 to 70 kV produces less penetrating dental x-rays with less energy and lon
quantity
this of the x-ray beam refers to the number of x-rays produced in the x-ray machine
amperage
determines the amount of electrons passing through the cathode filament, an increase in he number of electrons available to travel from the cathode to the anode results in the production of an increased number of x-rays
ampere
the unit of measure used to describe the number of electrons or current flowing through the cathode filament
impulses
what exposure time is measured in, because x-rays are created in a series of bursts and pulses rather than in a continuous stream, 1 impulse occurs every 1/60 of a second, or 60 impulses occur in 1 second
milliamperage
this regulates the temperature of the cathode filament. if it is increased the temp of the cathode filament increases, and consequently the number of electrons produced increases. an increased number of electrons that strike the anode increases the number
7-15
the mA in dental radiology is what?
density
an increase in mA increases the overall ______ of a radio graph and results in a darker image.
exposure time
milliamperage and _______ are inversely related, when altering the mA, this must be adjusted to maintain diagnostic density of an image. increase mA-descrease___, decrase mA-increase____
contrast
milliamperage affects ________.
intensity
is described as the product of the quantity (# of x-ray photons) and quality (energy of each photon) per unit of area per unit of time exposure. it is affected by kVp, mA, Exposure time, and distance.
distance
the _________ traveled by the x-ray beam affects the intensity of the beam
target surface distance
the distance from the source of radiation to the patients skin
target object distance
the distance from the source of radiation to the tooth
target receptor distance
the distance from the source of radiation to the receptor
inverse square law
the intensity of radiation is inversely proportioned to the square of the distance from the source of radiation. "inversely proportional" means that as one variable increases, the other decreases.
Wilhelm Conrad Roentgen
This Bavarian physicist discovered the x-ray on November 8, 1895
velocity
the speed of a wave of electromagnetic radiation.
frequency
the number of wavelengths that pass at a given point in a certain amount of time. this and wavelength are inversely related, ____ increased= short wavelength, decreased ___= long wavelength.
aluminum disks
these can be added to the tube head in 0.5mm increments, the purpose is to filter out the longer wavelengths, low-energy x-rays from the x-ray beam. the low-energy longer wavelength x-rays are harmful to the patient and are not useful in diagnostic radiol
total filtration
dental x-ray machines operating at or below 70 kVp require a minimum of 1.5mm of aluminum filtration, machines operating above 70 kVp require a minimum of 2.5mm aluminum filtration.
circular collimator
when using a _____ _____, federal regulations require that the x-ray beam be collimated to a diameter of no more than 2.75 inches as it exits from the PID and reaches the patients skin.
inherent filtration
this is approximately 0.5-1.0mm of aluminum**
this does not meet regulated standards by state and federal law
**
maximum permissible dose
MPD- the maximum dose equivalent that a body is permitted to receive within a specific period, it is the dose of radiation that a body can endure with little or no injury.
5.0/rems/year = 0.05/Sv/year
maximum permissible dose for occupationally exposed persons
0.1/rem/year = 0.001/Sv/year
maximum permissible dose for non-occupationally exposed persons, or pregnant women who are occupationally exposed
MAD
maximum accumulated dose, this is the maximum dose of radiation that a person can be exposed to in a lifetime. formula=MAD=(N-(persons age in years)-18) X 5 rems/year,
MAD=(N-18)X 0.5 Sv/year
primary beam
the dental radiographer must always avoid the _______
6 feet
radiographer must maintain a distance of at least _____ from the x-ray tube head, or stand behind a protective barrier wall
90-135 degree
radiographer must position themselves at a _______ angle to the primary beam, for protection
tissue sensitivity
how sensitive certain body tissues are to radiation exposure
most sensitive tissues
reproductive, lymphoid, bone marrow
least sensitive tissues
nervous system, skeletal system, mature bone
law of B & T
the faster the reproductive rate of the cells and tissues, the more sensitive they are to radiation, the more specialized the cells and tissues are the less sensitive to radiation they are
period of injury
this occurs after the latent period, following exposure to radiation, can include a variety of cellular injuries
recovery period
the period during which cellular damage caused by radiation is followed by repair
lethal dose
LD- 50/30, kill 50% of the population in 30 days
coulombs/kg
old name was rotengen= measures x-ray exposure in air
gray
old name was rad= measures x-rays absorbed by tissues
sievert
old name was rem= measures effects (damage) on man
erythmea
redness, the first sign of exposure to radiation
alopecia
loss of hair, a common sign of radiation exposure
fixer solution
a chemical solution used in processing; removes the unexposed silver halide crystals and creates white or clear (radiopaque) areas on film
10 mins, 1.5 mins
fixer time for manual processing is ____, and _____ for automatic processors
developer solution
a chemical solution used in film processing that distinguishes between exposed and unexposed silver halide crystals and makes the latent image visible.
5 mins, 1.5 mins
developer time for manual processing is _____, and ____ for automatic processors
68, 80
the temperature for developer solution for manual processing is ____ degrees, and ______ degrees fro automatic processing
the bisecting technique
this is based on a geometric principle of bisecting a triangle, the angle formed by the long axis of the teeth and the film is bisected, and the x-ray beam is directed perpendicular to the bisecting line, (perpendicular means at a right angle to the film)
brown film or image
this is a processing error that is caused by insufficient fixing or washing
black marks
this is an error made during processing caused by nail pressure to film,or possibly light or saliva leaks through the film packets
cone cut
a clear unexposed area on a dental radiograph that occurs when the PID is misaligned and the x-ray beam is not centered over the film
coronoid process
what is the only mandibular landmark that appears on a maxillary periapical?
X-Y formation
where the nasal fossa intersects with the maxillary sinus, usually near the lateral incisor or canine
mandibular foramen
you will not see this on a periapical or intra-oral shots
enamel
the most radiopaque and most calcified substance in the body, followed by cementum, and dentin
filaments heat
1st step in the process of producing x-rays
electrons released
2nd step in the process of producing x-rays
electron cloud forms
3rd step in process of producing x-rays
4th step in process of producing x-rays
high voltage circuit activated to create speed of electrons
stopping of target
5th step in the process of producing x-rays
x-rays are the product
the final step in the process of producing x-rays
dupilcator
identical copy of an extra/intra oral radio graph, this requires the use of a film dupilcator, a light source that is commercially available from the manufacturers, it provides a diffused light source that evenly exposes the special duplicating film
kVp change problem formula
increase kVp by 15, and decrease exposure time by 1/2.
mA change problem formula
mA's old=mA's new
(old) mA X sec = mA X (new) sec
film speed change problem formula
with each change in speed, the exposure time needed halves, with each decrease in speed, the exposure time needed doubles. A_F film speeds A=slowest, F=fastest.
intensity change problem formula
(new) intensity = (old) distance
(old) intensity = (new) distance
exposure time change problem formula
(new) exposure time = (new) distance
(old) exposure time = (old) distance
film fog
blurry film- little bit of exposure to the whole film, possible causes= incorrect filter, improper safe-light, incorrect bulb, or incorrect distance
differences in direct and indirect exposure
direct exposure film is exposed by x-rays, and indirect exposure film is exposed by florescent light from intensifying screens
outer wrapping of film
plastic that protects film from light and moisture
lead foil
helps protect the x-ray from scatter radiation, it has a herringbone imprint on it so it can detect if film was exposed backwards
black paper of film
goes around the front and back of film and helps protect the film from light and moisture if there is a leak in the outer wrapper
film
to capture and make a permanent image, has an outer protective coating on front and back
emulsion
on the front and back of film, contains silver halide and bromide crystals
energizes
when x-rays hit the crystals it ____ them, where the x-rays are blocked the crystals did not get ____. when processed the crystals that are ____ are radiolucent, and the ones not _______ are wiped away from fixer, these are radiolucent.
plastic base
base of film packet
description of latent image production
once the film is exposed, the crystals that are energized (the ones holding the image by holding the energy), the films have been exposed but they have not been processed yet
faster
the larger the crystals the _____ the speed
definition
faster film is less crisp and has less _____
bitewings
used to show the crowns of teeth, alveolar crest, and the interproximal area- taken once a year
periapicals
used to obtain a view of the entire tooth and its periodontal supporting structures
occlusals
used to show large areas of the maxilla, mandible, or the floor of the mouth
panoramic
used to show large areas of the maxillary and mandibular arches with adjacent structures
lateral oblique mandible
used to view the mandible from the canine region posteriorly to the body and ramus
TMJ survey
reveals the relationship of the head of the mandibular condyle in relation to the glenoid fossa of the temporal bone
posteroanterior survey
revelas the entire skull in the posteroanterior plane; often used as a supplement to the lateral skull survey
cephalometric
lateral skull- used in orthodontics to measure the head
occlusal
3X 2 1/4" Size no. 4 film speed D; used to visualize a cross section of an area